In many insects, X‐linked inversions fix at a higher rate and are much less polymorphic
than autosomal inversions. Here, we report that in Drosophila, X‐linked inversions
also capture 67% more genes. We estimated the number of genes captured
through an approximate Bayesian computational analysis of gene orders in nine species
of Drosophila. X‐linked inversions fixed with a significantly larger gene content.
Further, X‐linked inversions of intermediate size enjoy highest fixation rate, while
the fixation rate of autosomal inversions decreases with size. A less detailed analysis
in Anopheles suggests a similar pattern holds in mosquitoes. We develop a population
genetic model that assumes the fitness effects of inversions scale with the
number of genes captured. We show that the same conditions that lead to a higher
fixation rate also produce a larger size for inversions on the X.